#define _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>
int main()
{
    int n = 0;
    scanf("%d", &n);
    double sum = 0;
    for (int i = 1; i <= n; i++)
    {
        sum += 1.0 / i;
    }
    printf("%f\n", sum);

    return 0;
}